The present invention refers to a high-productivity apparatus for the orientation at a very fast rate of hollow plastic articles, in particular bottles, which have not a circular form, but have instead their body in the shape of a parallelepiped with a rectangular cross-section. In particular, the present invention applies in a preferred manner to the working steps that follow a phase of simultaneous blow moulding of a plurality of bottles with a rectangular cross-section.
Automatic plants for the production of hollow plastic bodies are known in the art to comprise a section in which preforms are preliminarily produced, and a section in which the preforms are then blow moulded into the final product.
Generally known in the art is also the possibility for the two sections to be either physically and functionally integrated into a single plant, which is then called a xe2x80x9csingle-stepxe2x80x9d plant, or physically and functionally subdivided into two distinct, autonomous plants, in which case reference is usually made to xe2x80x9ctwo-stepxe2x80x9d plants and processes.
The difference existing between single-step and two-step machines, along with the description thereof, is well-known to all those skilled in the art, so that it shall not be described or explained here any further.
The present invention applies to that section of a plant and that process that are solely used to blow mould, and therefore convert into a finished product, a previously produced preform, regardless of whether such a section belongs to a single-step plant or a double-step one.
In the production of plastic containers, especially bottles intended for use in the most varied applications, use is increasingly being made of a particular kind of bottle, i.e. bottles whose body is in the shape of a parallelepiped having a horizontal cross-section, with respect to the resting plane of the bottle, in the shape of a rectangle.
During the blow moulding operation, the above cited bottles are brought into a side-by-side arrangement, as illustrated in FIG. 1, and they are all oriented in such a manner as to ensure that the pairs of opposite walls of each bottle are either parallel or orthogonal to the plane passing through all axes of the bottles.
This solution, however, is connected with two particular kinds of drawbacks. First of all, if the case is faced which involves the presence of contours with undercuts on the walls, it becomes really difficult, and sometimes even impossible, to succeed in obtaining a smooth release of such walls from the mould, owing also to a kind of xe2x80x9cstickingxe2x80x9d effect that is particularly evident when the contact surface between mould and bottle is flat, i.e. plane, as in the case being considered here. In such a case, in fact, the whole extent of cohesive forces existing between bottle and mould must be overcome with an orthogonal release force and, therefore, with a maximum effort, although concentrated in a very short time. However, such a maximum effort cannot be available from the plant and this creates a number of evident technical and production-related problems.
The second drawback relates to the size of the blow moulding plant. Looking again at FIG. 1, it can quite easily be inferred that, if the bottles are in a rather large number and their major side is rather wide, then, owing to these bottles having to be brought into a side-by-side arrangement, they impose a correspondingly large size on the blow-moulding mould, with further problems as far as tightness, strength, rigidity, and control of the handling organs are among other things of concern, as those skilled in the art are well aware of.
Based on the above considerations, it is therefore desirable, and it is actually a main purpose of the present invention, to provide a plant and a respective process which are adapted to implement and carry out the blow-moulding phase of the described type, while doing away with the above mentioned kind of drawbacks, being fully reliable and capable of being easily implemented using readily available and, therefore, cost-effective materials and techniques.
Such an aim of the present invention, along with further features thereof, is reached in a plant and a process that are implemented and operate as recited in the appended claims.